Naked-eye stereoscopic image display apparatuses have traditionally been proposed which can provide a stereoscopic view without the need for special eyeglasses.
For example, in Patent Document 1, the stereoscopic image display apparatus is disclosed which includes a barrier generating means and an image display means. The barrier generating means generates, under electronic control, parallax barrier stripes through the use of transmission display elements. With the display screen being disposed at a predetermined distance behind the position in which the parallax barrier stripes are generated, the image display means can output and display a multidirectional image on the display screen during the stereoscopic image displaying. The multidirectional image includes strips of a left image and strips of a right image that are arranged in alternate order correspondently to the parallax barrier stripes.
Such stereoscopic image display apparatus is configured to generate barrier stripes electronically and to freely control and vary, for example, the shape (the number of the stripes, the width of the stripes, and intervals between the stripes), the position (phase), and the density of the generated barrier stripes. Thus, the stereoscopic image display apparatus is capable of serving as a two-dimensional image display apparatus and a stereoscopic image display apparatus, providing a compatible image display apparatus.
In Patent Document 2, the naked-eye stereoscopic image display apparatus is disclosed which includes an image display means, a light-blocking means, a sensor, and a region division movement control means. The image display means displays the striped left-eye image and the striped right-eye image in an alternate manner. The light-blocking means is configured to move the position of the light-blocking portion generating a binocular parallax effect with a pitch equal to a quarter of the pitch of the light-blocking portion. The sensor detects the movement of the observer's head in a horizontal direction and also detects whether the position of the observer's head is out of the preferred viewing range in an anterior-posterior direction. With the light-blocking means being subjected to the division into regions in the horizontal direction, when the position of the observer's head is out of the preferred viewing range in an anterior-posterior direction, the region division movement control means controls whether to move the position of the light-blocking portion of the light-blocking means for each region division obtained through the division into regions.
Even if the head of the observer's head moves to a position out of the preferred viewing position, the stereoscopic image display apparatus according to Patent Document 2 is capable of supplying the right-eye image to the right eye of the observer and supplying the left-eye image to the left eye of the observer by performing the movement control over the light-blocking portion and the display control over the image display means. This allows the observer to recognize a stereoscopic image.